276/011-1 was the pre war AMAL identification for the carb used on WD16H. It changed per 1940.
In the older VAOS lists it is noted as AM276/011
It is not known why AMAL changed the coding system.
The carb did not fysically change as far as I know, only the number.
276/406 is a number that can be found on many NOS body replacement parts.
276AE/1BE is a code for the entire carb and float chamber combination. 276, for the intake diameter AE for the carb indicating config (flange or tube fitting) jetting and valve sizes.
1BE for the description of the float chamber e.g. indicating a straight or tilted connection to the carb body.
